Combined insulating bushing and transformer



Oct. 20, 1931. w s, EDSALL 1,827,936

COMBINED INSULATING BUSHING AND TRANSFORMER Filed Nov. 28, 1930 2 Sheets-Sheet l Oct. 20, 1931. w. s. EDsALL COMBINED INSULATING BUSHING ND TRANSFORMER Filed Nov. 28, 1930 2 Sheets-Sheet 2 Patented Oct. 20, 1931 UNITED STATES PATENT OFFICE WILLIAM S. EDSALL, OF BELMONT, MASSACHUSETTS, ASSIGNOR T0 CONDIT ELECTRICAL MANUFACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS, A CORPORA- TION OF MASSACHUSETTS COMBINED INSULATING BUSHING AND TRANSFORMER Application led November 28, 1930. Serial No. 498,668.

This invention relates to combined high tension insulating bushings and transformers for supplying low tension power which is derived from the line connected with the bushing and the potential of whichpower va ries in proportion to the variation of voltage of the high tension terminal of the bushing.

t is desirable to derive a. certain amount of lowtension alternating current power from a high tension power for the purpose of supplying synchronism indicatingr devices that will indicate when two high tension line sections are in synchronism so that they can be connected together. For this purpose it is convenient to derive the low tension power through the electrostatic capacity of a high tension switch bushing in the manner disclosed in the J'ansson Patent No. 1,725,983, for instance. The amount of power that can be derived from the usual bushing in this manner is quite limited, however, and is hardly suiicient to actuate a synchronism indicating device in a positive manner. The low tension voltage is out of phase with the high tension voltage and thus special phase-correcting apparatus is necessitated. Furthermore, it is quite desirable additionally to utilize the low tension power to actuate metering instruments and some small power consuming auxiliary devices. The amount of power that can be supplied through the capacity of the high tension bushing is insufficient for this purpose. Consequently it is an object of the present invention to combine an electromagnetic transformer with a bushing and located internally of the enclosing shell thereof and having a high tension primary winding that is connected with the high tension terminal of the bushing so that low tension power can be derived from the secondary winding of the transformer at a potential which varies in accordance with the potential of the high tension terminal of the bushing and thus can be used for synchronization purposes without the necessity foremploying phase-correction devices and also is ample to actuate other auxiliary instruments and apparatus.

The, location of av transformer within the enclosing` shell of the bushing involves special conditions of transformer and stud design and disposition. In my concurrently filed application Serial No. 498,667, I have disclosed one particular construction. The present application discloses and claims another desirable construction.

An object of the present invention is the provision of an insulating bushing having a transformer therein and a high tension 1n-V sulated stud that passes through the transformer and particularly through the core thereof and is insulated therefrom.

A further object of the invention is the provision of a bushing having a transformer therein which is composed of a plurality of independent but electrically connected units, with the stud of the bushing passed through all the units.

A further object of the invention is the provision of a bushing having a transformer that is composed of a plurality of independent magnetic cores that are disposed in superposed order one above the other lengthwise of the bushing and each insulated from all the others and having high tension windings that are connected in series, combined with a bushing stud that connects the end terminals of the bushing and passes through all of the transformer units.

Another object of the invention is the provision of a construction as defined above wherein two insulated studs are connected in parallel between the bushing terminals and pass between the transformer units on opposite sides of parts thereof.

A further object is generally to improve the construction of high tension bushings and transformers.

Fig. 1 is a sectional elevation through an insulating bushing embodying the present invention.

Fig. 2 is a section taken along line 2-2 of Fig. 1.

Fig. 3 is a diagrammatic view illustrating the connection between the transformer units.

Fig. 4 is a View similar to Fig. 1 but illustrating a modified transformer and stud construction.

Fig. 5 is a section taken along line 5-5 of Fig. 4.

Fig. 6 is a diagram illustrating the electrical connections between 'the transformer units of Fig. 4.

The high tension insulating bushing iliustrated in Figs. l, 2 and 3, includes an insulating enclosing shell consisting of an intermediate metal tube 10 having a radially outstanding flange l2 at its upper end which overlies and constitutes the closure for the opening 14 in the casin 16 through which the bushing may be extended. The casing 16, may, for instance, comprise the casing of an electric switch, and the bushing herein shown may comprise one of the switch terminals. The flange l2 is secured to the casing 16 by bolts i8 or other suitable' attaching means. An insulating shell 2O of porcelain or other suitable insulating material and of inverted conical shape is located. under and in line with the boitom open end of the metal shell lO and is attached to an outstanding flange metal shell by means including an attaching iage 24 carried by said insulating l and bolts 26 which pass through both ie lou er end of sa line of the bushino' shell 30 that is mainly of straight cylindrical configuration and is open at the top and bottom is located in line with the open upper end of the metal shell 10 and is secured tiereto by means of an attaching flange 32 carried by said insulating shell and bolts 84 which pass through said flange and into the Flange l2 of said metal shell. Said shell 30 preferably is provided with outstanding insulating capes or petticoats 36. rEhe top of said shell 30 is provided with an upstanding necl 38 to which is secured a metal cap 40 that constitutes the base of an oil reservoir having a cylindrical side wall 42 which is transparent at least in part and has a cover 44 that constitutes the upper high tension terminal of the bushing. The shell is adapted to be filled with an insulating medium as oil fo1 instance, to a level that is within the oil reservoir so as to provide insulation for the parts of the bushing that are located within the enclosing shell.

Tl e high tension transformer that is contained within the shell comprises a plurality of sections having separate magnetic cores 46, 48, and 52. Said cores are similar in coniiguration and are of general rectangular shape aud have parallel side legs 54 and 56 and end legs 58 that connect the parallel legs and are arcuate in configuration and have a diameter that closely conforms with the internal diameter of the shell 30. The transformer cores are located within the shell 30 in vertically spaced relation and are maintained in such relation between insulating spacing' rings 60j 64, 66 and 68, the lower ring 68 resting upon the top of the metal tube 10 and the upper ring 60 engaging the reduced neck portion 38 of the shell 30 so that when the bushing is assembled the transformers and the rings are confined in the aforesaid and illustrated relation. Each of the cores has a pair of high tension windings 70 and 72 contained on the parallel legs 54 and 56 thereof. The lowermost transformer core in addition has a. low tension secondary winding 74 which is contained on the `leg 56 beside the primary high tension winding 72 thereon. The high tension windings 7 O and 72 of the units are connected in series as is illustrated in Fig. 3. The core of each unit is connected electrically at 76 with the connection between the two windings 70 and 72 thereon so that the core is at a potential that is half the potential that exists at the terminals of the two windings thereon, so that the insulation between the two coils and the core, and between the respective cores of the units is simplified. The high tension lead 78 of the uppermost coil 70 is connected to a connector 80 which` is secured electrically and mechanically to the upper high tension terminal cap 44 of the bushing. The low tension or ground terminal lead 82 of the coil 72 of the lowermost unit is connected by suitable means as a bolt 84 with the metal tube l0 and thus is at ground potential since the casing 16 is ordinarily grounded. Thus the windings 7'0 and 72 of the units are traversed by a current which is supplied by a high tension line that is adapted to be connected with the terminal cap 44 of the bushing and sets up a low potential in the secondary winding 74 that can supply ample power for synchronizing and other purposes. The potential of the secondary winding varies in proportion to the variation of voltage of the high tension terminal of the bushing so that it can be used for synchronizing purposes without the necessity for employing corrective apparatus. The low tension secondary leads 86 are led externally of the bushing shell through an insulating bushing 88 that is extended through the metal shell 10. The uppermost units having t-he cores 46, 48 and 50 constitute reactors which limit the current and voltage supplied to the lowermost or transformer unit having the core 52.

The design of the unit-s is such that there is a substantial space between the coils 70 and 72 of each unit which space is in the axial line of the bushing between the ends thereof and a bushing stud 90 is extended through said spaces. Said stud has a conductor 92 that at its upper end is connected to a connector 94 that passes through and is secured in the terminal cap 44 of the bushing and has means as clamping nuts 96 at its upper end by means of which a high tension conductor can be connected to said stud and terminal cap. The lower end of said stud is conassunse nected to a terminal 98 that passes through the opening 28 in the lower end of the lower insulating shell 20 and is secured to said shell in fluid tight relation in the passage 28 by suitable means that includes the clamping nut 100. The exposed end of said terminal 98 is adapted for connection with the electrical apparatus within the casing 16 or, if said apparatus is an electric switch, said terminal can carry a stationary switchA member, not shown. The conductor 92 of said stud is provided with insulation 102 of suitable dielectric strength to resist successfully the voltage applied to the stud. The insulation can be com osed of spirally wound paper tape. Prefera ly the stud is flexible so that it can be conveniently located in the bushing especially in the modified construction hereinafter to be disclosed, and, for this purpose, I prefer that the stud comprise a section of commercial flexible insulated high tension cable.

In the modification illustrated in Figs. 4, 5 and 6, the bushing includes the metal inter mediate tube or shell 10, the lower insulating shell 20, and the upper insulating shell 30 constructed and connected as previously described. The open top of the upper shell is closed by a metal cover 40a that has a flat top wall 104 from the middle of which neck 106 upstands and terminates in a radially outstanding flange 108 that constitutes the bottom wall of an oil reservoir that has an npstanding side wall 110 composed at least in part of transparent material. As herein shown the wall 110 consists of a glass shell which rests upon the flange 108 and is closed by a cap 112. A metal tube 114 that is open at the bottom and closed at the top is extended axially through said oil reservoir and is screw threaded at the bottom into the neck 106 and has screw threads 116 at the top on which the cap 112 is screw threaded whereby to secure the cap in position. The exposed end of the' tube 116 is provided with nuts 118 or other suitable means for clamping a high tension conductor thereto and said tube and cap 112 and cover 104 constitute the upper high tension terminal of the bushing. Said tube 114 is provided with one or more vertically elongated slots 120 through which oil in the interior of the bushing may have access to the oil reservoir. As in the construction illustrated in Fig. 1, the transformer comprises a plurality of units having cores 46a, 48a, 50a and 52a, which are located in vertically spaced relation within the insulating enclosing shell 30 and are maintained in such relation by the insulating tubes 60, 62, 64, 66 and 68. The magnetic cores in this modification, however, are circular in section and have a diameter that closely conforms with the internal diameter of the shell 30 so that they are restrained from lateral dis- I placement. The cores each have a single leg 54a which extends diametrically across the circular section of the core. Each leg carries a separate high tension winding 7 0a the mid portion of which is connected by a tap 76a to the core so that each core is at a voltage that is mid way between the voltages existing at the terminals of the windings thereon. The lowermost core 52a has, in addition, a low tension secondary winding 74a. As shown in Fig. 6, the high tension windings of all the cores are connected in series and the high tension lead 78a of the uppermost coil is connected by a suitable connector 80a to the terminal cover 104. The low tension or ground terminal 82a of the lower-most coil is connected as before with the ground tube 10. The low tension secondary leads 86a of the secondary winding 74a are extended externally of the enclosing shell through a suitable bushing 88a secured in the metal shell 10. In this construction sufliciently large spaces 120 are provided between the opposite portions of the circular section of each core and the middle windings 70a to receive a pair of bushing studs 122 and 124 respectively, which are passed through the aligned passages 120 of the various transformer units and are connected in parallel between the high tension terminals of the bushing. Said studs are spaced apart where they pass through the transformer units but are brought together therebelow and extend downwardly in proximity through the metal shell 10 and the porcelain shell 20. The conductors 126 and 128 of said studsat their lower ends are connected to a connector 130 which passes through the lower end of the shell 20 in an oil tight manner and constitutes the lower terminal of the bushing. The upper ends of said studs are separately connected to connectors 132 and 134 which pass through the flat wall 104 of the cover 40a and are secured thereto by means including nuts 136 and are thereby connected electrically with the high tension terminal of the bushing. The studs have insulation 138 thereon which may be such as has been described in connection with the stud 90. The studs preferably are flexible so that they can be bent into the configuration illustrated and for this purpose the minals, and a bushing stud which connects both of said terminals and passes through said transformer.

2. A high tension bushing including an in- 5 sulating enclosing shell having terminals at the ends thereof, a transformer located within said shell having a closed magnetic core and a high tension winding thereon one terminal of ,vhich is connected with one of said bushing terminals, and a bushing stud which is connected with both of said bushing terminals and passes through the core of said transformer.

3. A high tension insulating bushing including an enclosing` shell having an intermediate metal tube and insulating tubes on the opposite ends of said metal tube, terminals carried bv the ends of said insulating tubes, a transformer contained within said shell haring a primari.7 winding that is connected between one of said bushing terminals and said metal tube and a secondary winding having a low tension terminal that is eX- tended e.\;ternally of said shell, and bushing stud that conn cts raid terminals and is extenoed through said 1 isformer.

A high tension insulating bushing as defined in claim 3 wherein the transformer has a closed magnetic core and the stud is extended through said core.

5. A high tension insulating bushing including an insulating enclosing shell, a transformer located therein comprising a plurality of spaced and aligned transformer units, terminals on the ends of said shell, and a bushing stud which connects said terminals and is extended througl said transfo 1mer units.

6. A high tension insulating' bushing including an insulating enclosing shell having terminals at the ends thereof, a transformer located within said shell comprising a plurality of spaced magnetic cores having serially connected high tension windings thereon t `it are connected to one of said terminals and a low tension secondary winding on one of sai tores a d bushing stud which connects said terminals and is extended through said cores.

7. A high tension insulating bushing including an insulating enclosing shell having terminals at the ends thereof, a transformer located within said shell comprising a plurality of spaced magnetic cores having serially connected high tension windings thereon that are connected to one of said terminals and a low tension secondary winding on one of said cores, and a bushing stud which connects said terminals and is extended through said cores, said stud being' flexible.

S. A high tension insulating bushing inclueing an i `nsulating enclosing shell having terminals at the ends thereof, a transformer located within said shell comprising a plurality of `ated magnetic cores having serial- 55 ly connected high tension windings thereon that are connected to one of said terminals and a low tension secondary winding on one of said cores, and a bushing stud which connects said terminals and is extended through said cores, said stud comprising a conductor and insulation thereon and both being ilexible.

9. A high tension insulating bushing including an insulating enclosing shell having terminals at the ends thereof, a. transformer located within said shell comprisine' a plurality of spaced magnetic cores having serially connected high tension windings thereon that are connected to one of said terminals and a. low tension secondary winding on one of said cores, and a bushing stud which conneets said terminals and is extended through said cores, said stud comprising a flexible insulated high tension cable.

l0. A high tension insulating bushing including an insulating enclosing shell, a transformer contained therein comprising a plurality of spaced magnetic cores, insulating means which supports said cores and maintains them in spaced relation, serially connected high tension windings on said cores, terminals on the ends of said bushing, and an insulating high tension bushing stud that connects said terminals and is extended through said cores.

ll. A high tension insulating bushing in* cluding an enclosing shell comprising a metal tube, an insulating tube carried by said metal tube, terminals on the ends of said shell, a transformer located within said shell comprising a plurality of magnetic cores which are located in spaced relation within said insulating tube and above said metal tube, insulating means carried by said metal tube which supports said cores and maintains them in spaced relation, serially connected high tension windings carried by said cores and connected between one of said terminals and said metal tube, a secondary winding carried by one of said cores, and a bushing insulated stud connect-ing said terminals and extended through said cores.

l2. A high tension insulating bushing including an enclosing shell having a metal tube, an insulating tube carried by said metal tube, insulated terminals on the ends of said. shell, a transformer located within said shell comprising a plurality of magnetic cores which are spaced apart within said insulating tube, insulating means carried by said metal tube which supports said cores and maintains them in spaced relation, a pair of spaced opposed high tension windings carried by each of said cores, said windings of all of said cores being connected in series hetween one of said terminals and said metal tube, a secondary winding carried by one of said cores, and an insulated stu-d connectv ing said terminals and extended through said cores in the spaces between said high tension windings.

13. A high tension insulating bushing including an enclosing shell having terminals at the ends thereof, a transformer loca-ted within said shell comprising a magnetic core having spaced opposed windings thereon connected to one of said terminals, and an insulated stud connecting said terminals and extended through said windings.

14. A high tension insulating bushing l comprising an enclosing shell having terminals at the ends thereof, a transformer located within said shell comprising a plurality of separately spaced units, and a plurality of studs extended in parallel between said terminals and through said units.

15. A high tension insulating bushing comprising an enclosing shell including a metal tube, insulated tubes at the end of the metal tube, terminals at the ends of said insulating tubes, a transformer located within said shell comprising a plurality of separately spaced units having high tension windings thereon that are connected in series between one of said terminals and said metal tube, one of said units having a secondary winding, and a plurality of studs which are connected in parallel between said terminals and extended through said units.

16. A high tension insulating bushing comprising an enclosing shell having terminals on the ends thereof, a transformer located within said shell comprising a core that extends axially across said shell and has a winding thereon, and a pair of high tension bushings that are connected in parallel between said terminals and extend through said transformer on opposite sides of said winding.

17. The combination of an insulating shell having a terminal at one end, a transformer located within said insulating shell and having a low tension winding, and a high tension winding that is connected to said terminal, and an insulated conductor ythat is extended through said transformer and shell and is connected with said terminal.

18. The combination of an insulating shell having a terminal at one end, a transformer located within said shell comprising a plurality of units which are spaced from each other within said shell, said units having hlgh tension windings that are connected to said terminal, and an insulated conductor extended through said shell and said transformer units and connected with said terminal.

ried by said units and connected with said terminal, and an insulated conductor extended through said shell and said transformer units and having a connection with said terminal.

20. The combination of an insulating shell having a supporting base at one end and a high tension terminal at the other end, a transformer located therein having a magnetic core, primary and secondary windings thereon, the primary winding having a connection with said terminal, and an insulated conductor extended through said shell and said core and having a connection with said terminal.

21. The combination of an insulating shell having a supporting base at one end and a high tension terminal at the other end, a transformer located within said shell having a circular magnetic core provided with opposed legs, windings on said legs, and an insulated conductor extended through said shell and said core between said windings and having a connection with said terminal.

22. The combination of an insulating shell having a terminal at one end, a transformer located within said shell and having a magnetic core provided with transformer windings, and a pair of insulated conductors extended through said core and said shell and having connections with said terminal.

23. The combination of an insulating shell having a terminal at one end, a transformer located within said shell comprising aplurality of independent magnetic cores which are located in spaced relation within said shell, windings on said cores, and a pair of insulated conductors which are extended in parallel through said shell and through said cores and have connections with said terminal.

24. The combination of an insulating shell having a terminal at one end., a transformer located within said shell comprising a plurality of magnetic cores located in spaced relation lengthwise of said shell and having legs that extend across said shell and windings on said legs, and a pair of insulated conductors extended in parallel through said shell and through said cores on opposite sides of said legs and windings and having connections with said terminal.

In testimony whereof, I have signed my name to this specification.

WILLIAM S. EDSALL. 

